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The Independent JPEG Group's JPEG software v6b with arithmetic coding support

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Guido Vollbeding 1998-03-28 00:00:00 +00:00 committed by DRC
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JPEG arithmetic encoding and decoding portable software implementation
======================================================================
Release of 28-Mar-98 by Guido Vollbeding <guido@jpegclub.org>
=============================================================
Primary URLs:
http://sylvana.net/jpeg-ari/
(directory containing the actual archive files:)
http://sylvana.net/jpeg-ari/jpeg-ari-28mar98.tar.gz
http://sylvana.net/jpeg-ari/jpeg-ari.zip
DISCLAIMER
==========
This package is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
It is possible that certain products which can be built using this
software modules might form inventions protected by patent rights in
some countries (e.g. by patents about arithmetic coding algorithms
owned by IBM and AT&T in the USA). Provision of this software by the
author does NOT include any licenses for any patents.
In those countries where a patent license is required for certain
applications of this software modules, you will have to obtain such
a license yourself.
See Annex L in the JPEG spec for further information
and a list of relevant patents.
What is it?
===========
This is my implementation of the arithmetic encoding and decoding
back-end for JPEG as specified in the
ISO/IEC International Standard 10918-1 and CCITT Recommendation
ITU-T T.81, "Information Technology - Digital Compression and
Coding of Continuous-tone Still Images, Part 1: Requirements
and Guidelines".
Arithmetic coding is a state-of-the-art lossless entropy data
compression method which offers better compression performance
than the well-established Huffman entropy coding process.
The JPEG standard specifies a particular arithmetic coding scheme
to be used optionally as alternative to Huffman coding.
Who needs it?
=============
This package might be of interest for people who are looking for
enhanced state-of-the-art image compression technologies.
It is intended to provide a reasonable tool for experimental,
comparison and evaluation purposes.
See the Disclaimer above for restricted conditions of usage.
How does it work?
=================
This distribution is organized as add-on to the widespread
Independent JPEG Group's JPEG software.
Thus, once you managed to install the IJG software distribution
successfully, there should be no additional problems (portability
issues etc.) to incorporate this package into the library,
and usage is straightforward.
Transcode given JPEG files simply with a command like
jpegtran -arithmetic [-progressive] < orig.jpg > arit.jpg
into an arithmetic coded version LOSSLESSLY! Since there are
practically no applications in existence which can handle such
files, you can only transform it back with the same tool
jpegtran [-optimize] [-progressive] < arit.jpg > orig2.jpg
to verify correct operation.
Thus, you can easily verify the enhanced compression performance
of the arithmetic coding version compared to the Huffman (with
fixed or custom tables) version.
The claim to evaluate was that arithmetic coding gives an average
5-10% compression improvement against Huffman.
Early tests with this implementation support this claim, and you
can perform tests with own material.
Here are some actual results:
% ./jpegtran -optimize < testorig.jpg > testopt.jpg
% ./jpegtran -arithmetic < testorig.jpg > testarit.jpg
% ./jpegtran < testarit.jpg > testorig2.jpg
% ./jpegtran -arithmetic -progressive < testorig.jpg > testaritp.jpg
% ./jpegtran < testaritp.jpg > testorig3.jpg
% ./jpegtran -optimize < ../butterfly.jpg > ../buttopt.jpg
% ./jpegtran -progressive < ../butterfly.jpg > ../buttprog.jpg
% ./jpegtran -arithmetic < ../butterfly.jpg > ../buttarit.jpg
% ./jpegtran < ../buttarit.jpg > ../butterfly2.jpg
% ./jpegtran -arithmetic -progressive < ../butterfly.jpg > ../buttaritp.jpg
% ./jpegtran < ../buttaritp.jpg > ../butterfly3.jpg
% ls -l test*.jpg
-rw-r--r-- 1 guivol 5153 Apr 13 18:51 testarit.jpg
-rw-r--r-- 1 guivol 5186 Apr 13 18:51 testaritp.jpg
-rw-r--r-- 1 guivol 5756 Apr 2 15:10 testimg.jpg
-rw-r--r-- 1 guivol 5645 Apr 2 15:10 testimgp.jpg
-rw-r--r-- 1 guivol 5463 Apr 13 18:51 testopt.jpg
-rw-r--r-- 1 guivol 5770 Apr 2 15:10 testorig.jpg
-rw-r--r-- 1 guivol 5770 Apr 13 18:51 testorig2.jpg
-rw-r--r-- 1 guivol 5770 Apr 13 18:51 testorig3.jpg
-rw-r--r-- 1 guivol 5655 Apr 2 15:10 testprog.jpg
% ls -l ../butt*.jpg
-rw-r--r-- 1 guivol 460091 Apr 13 18:52 ../buttarit.jpg
-rw-r--r-- 1 guivol 453703 Apr 13 18:52 ../buttaritp.jpg
-rw-r--r-- 1 guivol 527823 Nov 19 18:41 ../butterfly.jpg
-rw-r--r-- 1 guivol 527823 Apr 13 18:52 ../butterfly2.jpg
-rw-r--r-- 1 guivol 527823 Apr 13 18:52 ../butterfly3.jpg
-rw-r--r-- 1 guivol 511834 Apr 13 18:52 ../buttopt.jpg
-rw-r--r-- 1 guivol 492237 Apr 13 18:52 ../buttprog.jpg
%
Note that arithmetic coding requires only a single processing
pass due to its fully-adaptive nature, and compared to one-pass
(fixed tables) Huffman the arithmetic coded version consistently
achieves 10% compression improvement.
Compared with two-pass (custom tables) Huffman the improvement
is 5-10%.
Note that I wasn't able yet to cross-check interoperability of
the produced files with other implementations.
Thus, I can't be sure that the files are compliant to the spec,
but I hope so and the tests support it.
The encoding and decoding processes should be correct anyway,
however, in the sense that they are complementary to each other
and thus retain data integrity.
I would appreciate any indications for compliance or interoperability
with other implementations from somebody.
Please let me know if you are able to cross-check something.
Installation
============
The installation is a 2-stage procedure:
1. Preparing the IJG package for potential incorporation
of the arithmetic coding feature.
2. Incorporation of the actual arithmetic coding modules
and enabling the feature for usage.
The reason for this 2-stage process is the hope to make
step 1 obsolete in future IJG releases.
The actual implementation should remain separate IMHO due
to the different usage conditions.
Step 1:
1.1. Copy all files from the subdirectory 'patchv6b' into
the IJG software's v6b source directory.
This includes minor patches to some files and 3 extra
files which hold place for the actual implementation.
1.2. Update your Makefile/Projectfile for the inclusion of
the 3 extra files. This will be done automatically
if you use a configure-generated makefile and type
'./configure' (reconfigure).
1.3. Recompile ('make').
See the file 'PATCHES' in 'patchv6b' for details.
Step 2:
2.1. Replace the 3 placeholder files by the actual implementation
modules.
2.2. Enable application support of the new features by #defining
C_ARITH_CODING_SUPPORTED and D_ARITH_CODING_SUPPORTED
in 'jmorecfg.h'.
2.3. Recompile ('make').
Note that I suggest to add 3 placeholder files to the IJG
distribution. This would remove the need for system-dependent
changes (Makefiles) and thus considerably simplify the actual
installation for systems without a configure-generated makefile.
References
==========
- The Independent JPEG Group's software
- JBIG-KIT lossless image compression library by Markus Kuhn
- William B. Pennebaker, Joan L. Mitchell:
"JPEG Still Image Data Compression Standard",
Van Nostrand Reinhold, 1993, ISBN 0-442-01272-1.
- jpeg-faq (http://www.faqs.org/faqs/jpeg-faq/)
- compression-faq (http://www.faqs.org/faqs/compression-faq/)

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/*
* jaricom.c
*
* Copyright (C) 1997, Guido Vollbeding <guivol@esc.de>.
* This file is NOT part of the Independent JPEG Group's software
* for legal reasons.
* See the accompanying README file for conditions of distribution and use.
*
* This file contains probability estimation tables for common use in
* arithmetic entropy encoding and decoding routines.
*
* This data represents Table D.2 in the JPEG spec (ISO/IEC IS 10918-1
* and CCITT Recommendation ITU-T T.81) and Table 24 in the JBIG spec
* (ISO/IEC IS 11544 and CCITT Recommendation ITU-T T.82).
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* The following #define specifies the packing of the four components
* into the compact INT32 representation.
* Note that this formula must match the actual arithmetic encoder
* and decoder implementation. The implementation has to be changed
* if this formula is changed.
* The current organisation is leaned on Markus Kuhn's JBIG
* implementation (jbig_tab.c).
*/
#define V(a,b,c,d) (((INT32)a << 16) | ((INT32)c << 8) | ((INT32)d << 7) | b)
const INT32 jaritab[113] = {
/*
* Index, Qe_Value, Next_Index_LPS, Next_Index_MPS, Switch_MPS
*/
/* 0 */ V( 0x5a1d, 1, 1, 1 ),
/* 1 */ V( 0x2586, 14, 2, 0 ),
/* 2 */ V( 0x1114, 16, 3, 0 ),
/* 3 */ V( 0x080b, 18, 4, 0 ),
/* 4 */ V( 0x03d8, 20, 5, 0 ),
/* 5 */ V( 0x01da, 23, 6, 0 ),
/* 6 */ V( 0x00e5, 25, 7, 0 ),
/* 7 */ V( 0x006f, 28, 8, 0 ),
/* 8 */ V( 0x0036, 30, 9, 0 ),
/* 9 */ V( 0x001a, 33, 10, 0 ),
/* 10 */ V( 0x000d, 35, 11, 0 ),
/* 11 */ V( 0x0006, 9, 12, 0 ),
/* 12 */ V( 0x0003, 10, 13, 0 ),
/* 13 */ V( 0x0001, 12, 13, 0 ),
/* 14 */ V( 0x5a7f, 15, 15, 1 ),
/* 15 */ V( 0x3f25, 36, 16, 0 ),
/* 16 */ V( 0x2cf2, 38, 17, 0 ),
/* 17 */ V( 0x207c, 39, 18, 0 ),
/* 18 */ V( 0x17b9, 40, 19, 0 ),
/* 19 */ V( 0x1182, 42, 20, 0 ),
/* 20 */ V( 0x0cef, 43, 21, 0 ),
/* 21 */ V( 0x09a1, 45, 22, 0 ),
/* 22 */ V( 0x072f, 46, 23, 0 ),
/* 23 */ V( 0x055c, 48, 24, 0 ),
/* 24 */ V( 0x0406, 49, 25, 0 ),
/* 25 */ V( 0x0303, 51, 26, 0 ),
/* 26 */ V( 0x0240, 52, 27, 0 ),
/* 27 */ V( 0x01b1, 54, 28, 0 ),
/* 28 */ V( 0x0144, 56, 29, 0 ),
/* 29 */ V( 0x00f5, 57, 30, 0 ),
/* 30 */ V( 0x00b7, 59, 31, 0 ),
/* 31 */ V( 0x008a, 60, 32, 0 ),
/* 32 */ V( 0x0068, 62, 33, 0 ),
/* 33 */ V( 0x004e, 63, 34, 0 ),
/* 34 */ V( 0x003b, 32, 35, 0 ),
/* 35 */ V( 0x002c, 33, 9, 0 ),
/* 36 */ V( 0x5ae1, 37, 37, 1 ),
/* 37 */ V( 0x484c, 64, 38, 0 ),
/* 38 */ V( 0x3a0d, 65, 39, 0 ),
/* 39 */ V( 0x2ef1, 67, 40, 0 ),
/* 40 */ V( 0x261f, 68, 41, 0 ),
/* 41 */ V( 0x1f33, 69, 42, 0 ),
/* 42 */ V( 0x19a8, 70, 43, 0 ),
/* 43 */ V( 0x1518, 72, 44, 0 ),
/* 44 */ V( 0x1177, 73, 45, 0 ),
/* 45 */ V( 0x0e74, 74, 46, 0 ),
/* 46 */ V( 0x0bfb, 75, 47, 0 ),
/* 47 */ V( 0x09f8, 77, 48, 0 ),
/* 48 */ V( 0x0861, 78, 49, 0 ),
/* 49 */ V( 0x0706, 79, 50, 0 ),
/* 50 */ V( 0x05cd, 48, 51, 0 ),
/* 51 */ V( 0x04de, 50, 52, 0 ),
/* 52 */ V( 0x040f, 50, 53, 0 ),
/* 53 */ V( 0x0363, 51, 54, 0 ),
/* 54 */ V( 0x02d4, 52, 55, 0 ),
/* 55 */ V( 0x025c, 53, 56, 0 ),
/* 56 */ V( 0x01f8, 54, 57, 0 ),
/* 57 */ V( 0x01a4, 55, 58, 0 ),
/* 58 */ V( 0x0160, 56, 59, 0 ),
/* 59 */ V( 0x0125, 57, 60, 0 ),
/* 60 */ V( 0x00f6, 58, 61, 0 ),
/* 61 */ V( 0x00cb, 59, 62, 0 ),
/* 62 */ V( 0x00ab, 61, 63, 0 ),
/* 63 */ V( 0x008f, 61, 32, 0 ),
/* 64 */ V( 0x5b12, 65, 65, 1 ),
/* 65 */ V( 0x4d04, 80, 66, 0 ),
/* 66 */ V( 0x412c, 81, 67, 0 ),
/* 67 */ V( 0x37d8, 82, 68, 0 ),
/* 68 */ V( 0x2fe8, 83, 69, 0 ),
/* 69 */ V( 0x293c, 84, 70, 0 ),
/* 70 */ V( 0x2379, 86, 71, 0 ),
/* 71 */ V( 0x1edf, 87, 72, 0 ),
/* 72 */ V( 0x1aa9, 87, 73, 0 ),
/* 73 */ V( 0x174e, 72, 74, 0 ),
/* 74 */ V( 0x1424, 72, 75, 0 ),
/* 75 */ V( 0x119c, 74, 76, 0 ),
/* 76 */ V( 0x0f6b, 74, 77, 0 ),
/* 77 */ V( 0x0d51, 75, 78, 0 ),
/* 78 */ V( 0x0bb6, 77, 79, 0 ),
/* 79 */ V( 0x0a40, 77, 48, 0 ),
/* 80 */ V( 0x5832, 80, 81, 1 ),
/* 81 */ V( 0x4d1c, 88, 82, 0 ),
/* 82 */ V( 0x438e, 89, 83, 0 ),
/* 83 */ V( 0x3bdd, 90, 84, 0 ),
/* 84 */ V( 0x34ee, 91, 85, 0 ),
/* 85 */ V( 0x2eae, 92, 86, 0 ),
/* 86 */ V( 0x299a, 93, 87, 0 ),
/* 87 */ V( 0x2516, 86, 71, 0 ),
/* 88 */ V( 0x5570, 88, 89, 1 ),
/* 89 */ V( 0x4ca9, 95, 90, 0 ),
/* 90 */ V( 0x44d9, 96, 91, 0 ),
/* 91 */ V( 0x3e22, 97, 92, 0 ),
/* 92 */ V( 0x3824, 99, 93, 0 ),
/* 93 */ V( 0x32b4, 99, 94, 0 ),
/* 94 */ V( 0x2e17, 93, 86, 0 ),
/* 95 */ V( 0x56a8, 95, 96, 1 ),
/* 96 */ V( 0x4f46, 101, 97, 0 ),
/* 97 */ V( 0x47e5, 102, 98, 0 ),
/* 98 */ V( 0x41cf, 103, 99, 0 ),
/* 99 */ V( 0x3c3d, 104, 100, 0 ),
/* 100 */ V( 0x375e, 99, 93, 0 ),
/* 101 */ V( 0x5231, 105, 102, 0 ),
/* 102 */ V( 0x4c0f, 106, 103, 0 ),
/* 103 */ V( 0x4639, 107, 104, 0 ),
/* 104 */ V( 0x415e, 103, 99, 0 ),
/* 105 */ V( 0x5627, 105, 106, 1 ),
/* 106 */ V( 0x50e7, 108, 107, 0 ),
/* 107 */ V( 0x4b85, 109, 103, 0 ),
/* 108 */ V( 0x5597, 110, 109, 0 ),
/* 109 */ V( 0x504f, 111, 107, 0 ),
/* 110 */ V( 0x5a10, 110, 111, 1 ),
/* 111 */ V( 0x5522, 112, 109, 0 ),
/* 112 */ V( 0x59eb, 112, 111, 1 )
};

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/*
* jcarith.c
*
* Copyright (C) 1997, Guido Vollbeding <guivol@esc.de>.
* This file is NOT part of the Independent JPEG Group's software
* for legal reasons.
* See the accompanying README file for conditions of distribution and use.
*
* This file contains portable arithmetic entropy encoding routines for JPEG
* (implementing the ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81).
*
* Both sequential and progressive modes are supported in this single module.
*
* Suspension is not currently supported in this module.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Expanded entropy encoder object for arithmetic encoding. */
typedef struct {
struct jpeg_entropy_encoder pub; /* public fields */
INT32 c; /* C register, base of coding interval, layout as in sec. D.1.3 */
INT32 a; /* A register, normalized size of coding interval */
INT32 sc; /* counter for stacked 0xFF values which might overflow */
INT32 zc; /* counter for pending 0x00 output values which might *
* be discarded at the end ("Pacman" termination) */
int ct; /* bit shift counter, determines when next byte will be written */
int buffer; /* buffer for most recent output byte != 0xFF */
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
int dc_context[MAX_COMPS_IN_SCAN]; /* context index for DC conditioning */
unsigned int restarts_to_go; /* MCUs left in this restart interval */
int next_restart_num; /* next restart number to write (0-7) */
/* Pointers to statistics areas (these workspaces have image lifespan) */
unsigned char * dc_stats[NUM_ARITH_TBLS];
unsigned char * ac_stats[NUM_ARITH_TBLS];
} arith_entropy_encoder;
typedef arith_entropy_encoder * arith_entropy_ptr;
/* The following two definitions specify the allocation chunk size
* for the statistics area.
* According to sections F.1.4.4.1.3 and F.1.4.4.2, we need at least
* 49 statistics bins for DC, and 245 statistics bins for AC coding.
* Note that we use one additional AC bin for codings with fixed
* probability (0.5), thus the minimum number for AC is 246.
*
* We use a compact representation with 1 byte per statistics bin,
* thus the numbers directly represent byte sizes.
* This 1 byte per statistics bin contains the meaning of the MPS
* (more probable symbol) in the highest bit (mask 0x80), and the
* index into the probability estimation state machine table
* in the lower bits (mask 0x7F).
*/
#define DC_STAT_BINS 64
#define AC_STAT_BINS 256
/* NOTE: Uncomment the following #define if you want to use the
* given formula for calculating the AC conditioning parameter Kx
* for spectral selection progressive coding in section G.1.3.2
* of the spec (Kx = Kmin + SRL (8 + Se - Kmin) 4).
* Although the spec and P&M authors claim that this "has proven
* to give good results for 8 bit precision samples", I'm not
* convinced yet that this is really beneficial.
* Early tests gave only very marginal compression enhancements
* (a few - around 5 or so - bytes even for very large files),
* which would turn out rather negative if we'd suppress the
* DAC (Define Arithmetic Conditioning) marker segments for
* the default parameters in the future.
* Note that currently the marker writing module emits 12-byte
* DAC segments for a full-component scan in a color image.
* This is not worth worrying about IMHO. However, since the
* spec defines the default values to be used if the tables
* are omitted (unlike Huffman tables, which are required
* anyway), one might optimize this behaviour in the future,
* and then it would be disadvantageous to use custom tables if
* they don't provide sufficient gain to exceed the DAC size.
*
* On the other hand, I'd consider it as a reasonable result
* that the conditioning has no significant influence on the
* compression performance. This means that the basic
* statistical model is already rather stable.
*
* Thus, at the moment, we use the default conditioning values
* anyway, and do not use the custom formula.
*
#define CALCULATE_SPECTRAL_CONDITIONING
*/
/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
* We assume that int right shift is unsigned if INT32 right shift is,
* which should be safe.
*/
#ifdef RIGHT_SHIFT_IS_UNSIGNED
#define ISHIFT_TEMPS int ishift_temp;
#define IRIGHT_SHIFT(x,shft) \
((ishift_temp = (x)) < 0 ? \
(ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
(ishift_temp >> (shft)))
#else
#define ISHIFT_TEMPS
#define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
#endif
LOCAL(void)
emit_byte (int val, j_compress_ptr cinfo)
/* Write next output byte; we do not support suspension in this module. */
{
struct jpeg_destination_mgr * dest = cinfo->dest;
*dest->next_output_byte++ = (JOCTET) val;
if (--dest->free_in_buffer == 0)
if (! (*dest->empty_output_buffer) (cinfo))
ERREXIT(cinfo, JERR_CANT_SUSPEND);
}
/*
* Finish up at the end of an arithmetic-compressed scan.
*/
METHODDEF(void)
finish_pass (j_compress_ptr cinfo)
{
arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy;
INT32 temp;
/* Section D.1.8: Termination of encoding */
/* Find the e->c in the coding interval with the largest
* number of trailing zero bits */
if ((temp = (e->a - 1 + e->c) & 0xFFFF0000L) < e->c)
e->c = temp + 0x8000L;
else
e->c = temp;
/* Send remaining bytes to output */
e->c <<= e->ct;
if (e->c & 0xF8000000L) {
/* One final overflow has to be handled */
if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer + 1, cinfo);
if (e->buffer + 1 == 0xFF)
emit_byte(0x00, cinfo);
}
e->zc += e->sc; /* carry-over converts stacked 0xFF bytes to 0x00 */
e->sc = 0;
} else {
if (e->buffer == 0)
++e->zc;
else if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer, cinfo);
}
if (e->sc) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
do {
emit_byte(0xFF, cinfo);
emit_byte(0x00, cinfo);
} while (--e->sc);
}
}
/* Output final bytes only if they are not 0x00 */
if (e->c & 0x7FFF800L) {
if (e->zc) /* output final pending zero bytes */
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte((e->c >> 19) & 0xFF, cinfo);
if (((e->c >> 19) & 0xFF) == 0xFF)
emit_byte(0x00, cinfo);
if (e->c & 0x7F800L) {
emit_byte((e->c >> 11) & 0xFF, cinfo);
if (((e->c >> 11) & 0xFF) == 0xFF)
emit_byte(0x00, cinfo);
}
}
}
/*
* The core arithmetic encoding routine (common in JPEG and JBIG).
* This needs to go as fast as possible.
* Machine-dependent optimization facilities
* are not utilized in this portable implementation.
* However, this code should be fairly efficient and
* may be a good base for further optimizations anyway.
*
* Parameter 'val' to be encoded may be 0 or 1 (binary decision).
*
* Note: I've added full "Pacman" termination support to the
* byte output routines, which is equivalent to the optional
* Discard_final_zeros procedure (Figure D.15) in the spec.
* Thus, we always produce the shortest possible output
* stream compliant to the spec (no trailing zero bytes,
* except for FF stuffing).
*
* I've also introduced a new scheme for accessing
* the probability estimation state machine table,
* derived from Markus Kuhn's JBIG implementation.
*/
LOCAL(void)
arith_encode (j_compress_ptr cinfo, unsigned char *st, int val)
{
extern const INT32 jaritab[];
register arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy;
register unsigned char nl, nm;
register INT32 qe, temp;
register int sv;
/* Fetch values from our compact representation of Table D.2:
* Qe values and probability estimation state machine
*/
sv = *st;
qe = jaritab[sv & 0x7F]; /* => Qe_Value */
nl = qe & 0xFF; qe >>= 8; /* Next_Index_LPS + Switch_MPS */
nm = qe & 0xFF; qe >>= 8; /* Next_Index_MPS */
/* Encode & estimation procedures per sections D.1.4 & D.1.5 */
e->a -= qe;
if (val != (sv >> 7)) {
/* Encode the less probable symbol */
if (e->a >= qe) {
/* If the interval size (qe) for the less probable symbol (LPS)
* is larger than the interval size for the MPS, then exchange
* the two symbols for coding efficiency, otherwise code the LPS
* as usual: */
e->c += e->a;
e->a = qe;
}
*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
} else {
/* Encode the more probable symbol */
if (e->a >= 0x8000L)
return; /* A >= 0x8000 -> ready, no renormalization required */
if (e->a < qe) {
/* If the interval size (qe) for the less probable symbol (LPS)
* is larger than the interval size for the MPS, then exchange
* the two symbols for coding efficiency: */
e->c += e->a;
e->a = qe;
}
*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
}
/* Renormalization & data output per section D.1.6 */
do {
e->a <<= 1;
e->c <<= 1;
if (--e->ct == 0) {
/* Another byte is ready for output */
temp = e->c >> 19;
if (temp > 0xFF) {
/* Handle overflow over all stacked 0xFF bytes */
if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer + 1, cinfo);
if (e->buffer + 1 == 0xFF)
emit_byte(0x00, cinfo);
}
e->zc += e->sc; /* carry-over converts stacked 0xFF bytes to 0x00 */
e->sc = 0;
/* Note: The 3 spacer bits in the C register guarantee
* that the new buffer byte can't be 0xFF here
* (see page 160 in the P&M JPEG book). */
e->buffer = temp & 0xFF; /* new output byte, might overflow later */
} else if (temp == 0xFF) {
++e->sc; /* stack 0xFF byte (which might overflow later) */
} else {
/* Output all stacked 0xFF bytes, they will not overflow any more */
if (e->buffer == 0)
++e->zc;
else if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer, cinfo);
}
if (e->sc) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
do {
emit_byte(0xFF, cinfo);
emit_byte(0x00, cinfo);
} while (--e->sc);
}
e->buffer = temp & 0xFF; /* new output byte (can still overflow) */
}
e->c &= 0x7FFFFL;
e->ct += 8;
}
} while (e->a < 0x8000L);
}
/*
* Emit a restart marker & resynchronize predictions.
*/
LOCAL(void)
emit_restart (j_compress_ptr cinfo, int restart_num)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci;
jpeg_component_info * compptr;
finish_pass(cinfo);
emit_byte(0xFF, cinfo);
emit_byte(JPEG_RST0 + restart_num, cinfo);
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* Re-initialize statistics areas */
if (cinfo->progressive_mode == 0 || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
MEMZERO(entropy->dc_stats[compptr->dc_tbl_no], DC_STAT_BINS);
/* Reset DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
if (cinfo->progressive_mode == 0 || cinfo->Ss) {
MEMZERO(entropy->ac_stats[compptr->ac_tbl_no], AC_STAT_BINS);
}
}
/* Reset arithmetic encoding variables */
entropy->c = 0;
entropy->a = 0x10000L;
entropy->sc = 0;
entropy->zc = 0;
entropy->ct = 11;
entropy->buffer = -1; /* empty */
}
/*
* MCU encoding for DC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl;
int v, v2, m;
ISHIFT_TEMPS
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
tbl = cinfo->cur_comp_info[ci]->dc_tbl_no;
/* Compute the DC value after the required point transform by Al.
* This is simply an arithmetic right shift.
*/
m = IRIGHT_SHIFT((int) ((*block)[0]), cinfo->Al);
/* Sections F.1.4.1 & F.1.4.4.1: Encoding of DC coefficients */
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.4: Encode_DC_DIFF */
if ((v = m - entropy->last_dc_val[ci]) == 0) {
arith_encode(cinfo, st, 0);
entropy->dc_context[ci] = 0; /* zero diff category */
} else {
entropy->last_dc_val[ci] = m;
arith_encode(cinfo, st, 1);
/* Figure F.6: Encoding nonzero value v */
/* Figure F.7: Encoding the sign of v */
if (v > 0) {
arith_encode(cinfo, st + 1, 0); /* Table F.4: SS = S0 + 1 */
st += 2; /* Table F.4: SP = S0 + 2 */
entropy->dc_context[ci] = 4; /* small positive diff category */
} else {
v = -v;
arith_encode(cinfo, st + 1, 1); /* Table F.4: SS = S0 + 1 */
st += 3; /* Table F.4: SN = S0 + 3 */
entropy->dc_context[ci] = 8; /* small negative diff category */
}
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
arith_encode(cinfo, st, 0);
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) (((INT32) 1 << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) (((INT32) 1 << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] += 8; /* large diff category */
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
}
return TRUE;
}
/*
* MCU encoding for AC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int tbl, k, ke;
int v, v2, m;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data block */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
/* Sections F.1.4.2 & F.1.4.4.2: Encoding of AC coefficients */
/* Establish EOB (end-of-block) index */
for (ke = cinfo->Se + 1; ke > 1; ke--)
/* We must apply the point transform by Al. For AC coefficients this
* is an integer division with rounding towards 0. To do this portably
* in C, we shift after obtaining the absolute value.
*/
if ((v = (*block)[jpeg_natural_order[ke - 1]]) >= 0) {
if (v >>= cinfo->Al) break;
} else {
v = -v;
if (v >>= cinfo->Al) break;
}
/* Figure F.5: Encode_AC_Coefficients */
for (k = cinfo->Ss; k < ke; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 0); /* EOB decision */
entropy->ac_stats[tbl][245] = 0;
for (;;) {
if ((v = (*block)[jpeg_natural_order[k]]) >= 0) {
if (v >>= cinfo->Al) {
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->ac_stats[tbl] + 245, 0);
break;
}
} else {
v = -v;
if (v >>= cinfo->Al) {
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->ac_stats[tbl] + 245, 1);
break;
}
}
arith_encode(cinfo, st + 1, 0); st += 3; k++;
}
st += 2;
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
if (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
}
arith_encode(cinfo, st, 0);
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
/* Encode EOB decision only if k <= cinfo->Se */
if (k <= cinfo->Se) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 1);
}
return TRUE;
}
/*
* MCU encoding for DC successive approximation refinement scan.
*/
METHODDEF(boolean)
encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
unsigned char st[4];
int Al, blkn;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
Al = cinfo->Al;
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
st[0] = 0; /* use fixed probability estimation */
/* We simply emit the Al'th bit of the DC coefficient value. */
arith_encode(cinfo, st, (MCU_data[blkn][0][0] >> Al) & 1);
}
return TRUE;
}
/*
* MCU encoding for AC successive approximation refinement scan.
*/
METHODDEF(boolean)
encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int tbl, k, ke, kex;
int v;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data block */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
/* Section G.1.3.3: Encoding of AC coefficients */
/* Establish EOB (end-of-block) index */
for (ke = cinfo->Se + 1; ke > 1; ke--)
/* We must apply the point transform by Al. For AC coefficients this
* is an integer division with rounding towards 0. To do this portably
* in C, we shift after obtaining the absolute value.
*/
if ((v = (*block)[jpeg_natural_order[ke - 1]]) >= 0) {
if (v >>= cinfo->Al) break;
} else {
v = -v;
if (v >>= cinfo->Al) break;
}
/* Establish EOBx (previous stage end-of-block) index */
for (kex = ke; kex > 1; kex--)
if ((v = (*block)[jpeg_natural_order[kex - 1]]) >= 0) {
if (v >>= cinfo->Ah) break;
} else {
v = -v;
if (v >>= cinfo->Ah) break;
}
/* Figure G.10: Encode_AC_Coefficients_SA */
for (k = cinfo->Ss; k < ke; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (k >= kex)
arith_encode(cinfo, st, 0); /* EOB decision */
entropy->ac_stats[tbl][245] = 0;
for (;;) {
if ((v = (*block)[jpeg_natural_order[k]]) >= 0) {
if (v >>= cinfo->Al) {
if (v >> 1) /* previously nonzero coef */
arith_encode(cinfo, st + 2, (v & 1));
else { /* newly nonzero coef */
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->ac_stats[tbl] + 245, 0);
}
break;
}
} else {
v = -v;
if (v >>= cinfo->Al) {
if (v >> 1) /* previously nonzero coef */
arith_encode(cinfo, st + 2, (v & 1));
else { /* newly nonzero coef */
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->ac_stats[tbl] + 245, 1);
}
break;
}
}
arith_encode(cinfo, st + 1, 0); st += 3; k++;
}
}
/* Encode EOB decision only if k <= cinfo->Se */
if (k <= cinfo->Se) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 1);
}
return TRUE;
}
/*
* Encode and output one MCU's worth of arithmetic-compressed coefficients.
*/
METHODDEF(boolean)
encode_mcu (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
jpeg_component_info * compptr;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl, k, ke;
int v, v2, m;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
/* Sections F.1.4.1 & F.1.4.4.1: Encoding of DC coefficients */
tbl = compptr->dc_tbl_no;
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.4: Encode_DC_DIFF */
if ((v = (*block)[0] - entropy->last_dc_val[ci]) == 0) {
arith_encode(cinfo, st, 0);
entropy->dc_context[ci] = 0; /* zero diff category */
} else {
entropy->last_dc_val[ci] = (*block)[0];
arith_encode(cinfo, st, 1);
/* Figure F.6: Encoding nonzero value v */
/* Figure F.7: Encoding the sign of v */
if (v > 0) {
arith_encode(cinfo, st + 1, 0); /* Table F.4: SS = S0 + 1 */
st += 2; /* Table F.4: SP = S0 + 2 */
entropy->dc_context[ci] = 4; /* small positive diff category */
} else {
v = -v;
arith_encode(cinfo, st + 1, 1); /* Table F.4: SS = S0 + 1 */
st += 3; /* Table F.4: SN = S0 + 3 */
entropy->dc_context[ci] = 8; /* small negative diff category */
}
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
arith_encode(cinfo, st, 0);
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) (((INT32) 1 << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) (((INT32) 1 << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] += 8; /* large diff category */
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
/* Sections F.1.4.2 & F.1.4.4.2: Encoding of AC coefficients */
tbl = compptr->ac_tbl_no;
/* Establish EOB (end-of-block) index */
for (ke = DCTSIZE2; ke > 1; ke--)
if ((*block)[jpeg_natural_order[ke - 1]]) break;
/* Figure F.5: Encode_AC_Coefficients */
for (k = 1; k < ke; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 0); /* EOB decision */
while ((v = (*block)[jpeg_natural_order[k]]) == 0) {
arith_encode(cinfo, st + 1, 0); st += 3; k++;
}
arith_encode(cinfo, st + 1, 1);
/* Figure F.6: Encoding nonzero value v */
/* Figure F.7: Encoding the sign of v */
entropy->ac_stats[tbl][245] = 0;
if (v > 0) {
arith_encode(cinfo, entropy->ac_stats[tbl] + 245, 0);
} else {
v = -v;
arith_encode(cinfo, entropy->ac_stats[tbl] + 245, 1);
}
st += 2;
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
if (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
}
arith_encode(cinfo, st, 0);
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
/* Encode EOB decision only if k < DCTSIZE2 */
if (k < DCTSIZE2) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 1);
}
}
return TRUE;
}
/*
* Initialize for an arithmetic-compressed scan.
*/
METHODDEF(void)
start_pass (j_compress_ptr cinfo, boolean gather_statistics)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci, tbl;
jpeg_component_info * compptr;
if (gather_statistics)
/* Make sure to avoid that in the master control logic!
* We are fully adaptive here and need no extra
* statistics gathering pass!
*/
ERREXIT(cinfo, JERR_NOT_COMPILED);
/* We assume jcmaster.c already validated the progressive scan parameters. */
/* Select execution routines */
if (cinfo->progressive_mode) {
if (cinfo->Ah == 0) {
if (cinfo->Ss == 0)
entropy->pub.encode_mcu = encode_mcu_DC_first;
else
entropy->pub.encode_mcu = encode_mcu_AC_first;
} else {
if (cinfo->Ss == 0)
entropy->pub.encode_mcu = encode_mcu_DC_refine;
else
entropy->pub.encode_mcu = encode_mcu_AC_refine;
}
} else
entropy->pub.encode_mcu = encode_mcu;
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* Allocate & initialize requested statistics areas */
if (cinfo->progressive_mode == 0 || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
tbl = compptr->dc_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->dc_stats[tbl] == NULL)
entropy->dc_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, DC_STAT_BINS);
MEMZERO(entropy->dc_stats[tbl], DC_STAT_BINS);
/* Initialize DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
if (cinfo->progressive_mode == 0 || cinfo->Ss) {
tbl = compptr->ac_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->ac_stats[tbl] == NULL)
entropy->ac_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, AC_STAT_BINS);
MEMZERO(entropy->ac_stats[tbl], AC_STAT_BINS);
#ifdef CALCULATE_SPECTRAL_CONDITIONING
if (cinfo->progressive_mode)
/* Section G.1.3.2: Set appropriate arithmetic conditioning value Kx */
cinfo->arith_ac_K[tbl] = cinfo->Ss + ((8 + cinfo->Se - cinfo->Ss) >> 4);
#endif
}
}
/* Initialize arithmetic encoding variables */
entropy->c = 0;
entropy->a = 0x10000L;
entropy->sc = 0;
entropy->zc = 0;
entropy->ct = 11;
entropy->buffer = -1; /* empty */
/* Initialize restart stuff */
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num = 0;
}
/*
* Module initialization routine for arithmetic entropy encoding.
*/
GLOBAL(void)
jinit_arith_encoder (j_compress_ptr cinfo)
{
arith_entropy_ptr entropy;
int i;
entropy = (arith_entropy_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(arith_entropy_encoder));
cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
entropy->pub.start_pass = start_pass;
entropy->pub.finish_pass = finish_pass;
/* Mark tables unallocated */
for (i = 0; i < NUM_ARITH_TBLS; i++) {
entropy->dc_stats[i] = NULL;
entropy->ac_stats[i] = NULL;
}
}

6
jcinit.c
View File

@ -41,9 +41,9 @@ jinit_compress_master (j_compress_ptr cinfo)
/* Forward DCT */
jinit_forward_dct(cinfo);
/* Entropy encoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
} else {
if (cinfo->arith_code)
jinit_arith_encoder(cinfo);
else {
if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED
jinit_phuff_encoder(cinfo);

5
jcmarker.c
View File

@ -529,7 +529,10 @@ write_frame_header (j_compress_ptr cinfo)
/* Emit the proper SOF marker */
if (cinfo->arith_code) {
emit_sof(cinfo, M_SOF9); /* SOF code for arithmetic coding */
if (cinfo->progressive_mode)
emit_sof(cinfo, M_SOF10); /* SOF code for progressive arithmetic */
else
emit_sof(cinfo, M_SOF9); /* SOF code for sequential arithmetic */
} else {
if (cinfo->progressive_mode)
emit_sof(cinfo, M_SOF2); /* SOF code for progressive Huffman */

4
jcmaster.c
View File

@ -433,7 +433,7 @@ prepare_for_pass (j_compress_ptr cinfo)
/* Do Huffman optimization for a scan after the first one. */
select_scan_parameters(cinfo);
per_scan_setup(cinfo);
if (cinfo->Ss != 0 || cinfo->Ah == 0 || cinfo->arith_code) {
if (cinfo->Ss != 0 || cinfo->Ah == 0) {
(*cinfo->entropy->start_pass) (cinfo, TRUE);
(*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
master->pub.call_pass_startup = FALSE;
@ -567,7 +567,7 @@ jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
cinfo->num_scans = 1;
}
if (cinfo->progressive_mode) /* TEMPORARY HACK ??? */
if (cinfo->progressive_mode && cinfo->arith_code == 0) /* TEMPORARY HACK ??? */
cinfo->optimize_coding = TRUE; /* assume default tables no good for progressive mode */
/* Initialize my private state */

2
jctrans.c
View File

@ -167,7 +167,7 @@ transencode_master_selection (j_compress_ptr cinfo,
/* Entropy encoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
jinit_arith_encoder(cinfo);
} else {
if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED

762
jdarith.c Normal file
View File

@ -0,0 +1,762 @@
/*
* jdarith.c
*
* Copyright (C) 1997, Guido Vollbeding <guivol@esc.de>.
* This file is NOT part of the Independent JPEG Group's software
* for legal reasons.
* See the accompanying README file for conditions of distribution and use.
*
* This file contains portable arithmetic entropy decoding routines for JPEG
* (implementing the ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81).
*
* Both sequential and progressive modes are supported in this single module.
*
* Suspension is not currently supported in this module.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Expanded entropy decoder object for arithmetic decoding. */
typedef struct {
struct jpeg_entropy_decoder pub; /* public fields */
INT32 c; /* C register, base of coding interval + input bit buffer */
INT32 a; /* A register, normalized size of coding interval */
int ct; /* bit shift counter, # of bits left in bit buffer part of C */
/* init: ct = -16 */
/* run: ct = 0..7 */
/* error: ct = -1 */
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
int dc_context[MAX_COMPS_IN_SCAN]; /* context index for DC conditioning */
unsigned int restarts_to_go; /* MCUs left in this restart interval */
/* Pointers to statistics areas (these workspaces have image lifespan) */
unsigned char * dc_stats[NUM_ARITH_TBLS];
unsigned char * ac_stats[NUM_ARITH_TBLS];
} arith_entropy_decoder;
typedef arith_entropy_decoder * arith_entropy_ptr;
/* The following two definitions specify the allocation chunk size
* for the statistics area.
* According to sections F.1.4.4.1.3 and F.1.4.4.2, we need at least
* 49 statistics bins for DC, and 245 statistics bins for AC coding.
* Note that we use one additional AC bin for codings with fixed
* probability (0.5), thus the minimum number for AC is 246.
*
* We use a compact representation with 1 byte per statistics bin,
* thus the numbers directly represent byte sizes.
* This 1 byte per statistics bin contains the meaning of the MPS
* (more probable symbol) in the highest bit (mask 0x80), and the
* index into the probability estimation state machine table
* in the lower bits (mask 0x7F).
*/
#define DC_STAT_BINS 64
#define AC_STAT_BINS 256
LOCAL(int)
get_byte (j_decompress_ptr cinfo)
/* Read next input byte; we do not support suspension in this module. */
{
struct jpeg_source_mgr * src = cinfo->src;
if (src->bytes_in_buffer == 0)
if (! (*src->fill_input_buffer) (cinfo))
ERREXIT(cinfo, JERR_CANT_SUSPEND);
src->bytes_in_buffer--;
return GETJOCTET(*src->next_input_byte++);
}
/*
* The core arithmetic decoding routine (common in JPEG and JBIG).
* This needs to go as fast as possible.
* Machine-dependent optimization facilities
* are not utilized in this portable implementation.
* However, this code should be fairly efficient and
* may be a good base for further optimizations anyway.
*
* Return value is 0 or 1 (binary decision).
*
* Note: I've changed the handling of the code base & bit
* buffer register C compared to other implementations
* based on the standards layout & procedures.
* While it also contains both the actual base of the
* coding interval (16 bits) and the next-bits buffer,
* the cut-point between these two parts is floating
* (instead of fixed) with the bit shift counter CT.
* Thus, we also need only one (variable instead of
* fixed size) shift for the LPS/MPS decision, and
* we can get away with any renormalization update
* of C (except for new data insertion, of course).
*
* I've also introduced a new scheme for accessing
* the probability estimation state machine table,
* derived from Markus Kuhn's JBIG implementation.
*/
LOCAL(int)
arith_decode (j_decompress_ptr cinfo, unsigned char *st)
{
extern const INT32 jaritab[];
register arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy;
register unsigned char nl, nm;
register INT32 qe, temp;
register int sv, data;
/* Renormalization & data input per section D.2.6 */
while (e->a < 0x8000L) {
if (--e->ct < 0) {
/* Need to fetch next data byte */
if (cinfo->unread_marker)
data = 0; /* stuff zero data */
else {
data = get_byte(cinfo); /* read next input byte */
if (data == 0xFF) { /* zero stuff or marker code */
do data = get_byte(cinfo);
while (data == 0xFF); /* swallow extra 0xFF bytes */
if (data == 0)
data = 0xFF; /* discard stuffed zero byte */
else {
/* Note: Different from the Huffman decoder, hitting
* a marker while processing the compressed data
* segment is legal in arithmetic coding.
* The convention is to supply zero data
* then until decoding is complete.
*/
cinfo->unread_marker = data;
data = 0;
}
}
}
e->c = (e->c << 8) | data; /* insert data into C register */
if ((e->ct += 8) < 0) /* update bit shift counter */
/* Need more initial bytes */
if (++e->ct == 0)
/* Got 2 initial bytes -> re-init A and exit loop */
e->a = 0x8000L; /* => e->a = 0x10000L after loop exit */
}
e->a <<= 1;
}
/* Fetch values from our compact representation of Table D.2:
* Qe values and probability estimation state machine
*/
sv = *st;
qe = jaritab[sv & 0x7F]; /* => Qe_Value */
nl = qe & 0xFF; qe >>= 8; /* Next_Index_LPS + Switch_MPS */
nm = qe & 0xFF; qe >>= 8; /* Next_Index_MPS */
/* Decode & estimation procedures per sections D.2.4 & D.2.5 */
temp = e->a - qe;
e->a = temp;
temp <<= e->ct;
if (e->c >= temp) {
e->c -= temp;
/* Conditional LPS (less probable symbol) exchange */
if (e->a < qe) {
e->a = qe;
*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
} else {
e->a = qe;
*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
sv ^= 0x80; /* Exchange LPS/MPS */
}
} else if (e->a < 0x8000L) {
/* Conditional MPS (more probable symbol) exchange */
if (e->a < qe) {
*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
sv ^= 0x80; /* Exchange LPS/MPS */
} else {
*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
}
}
return sv >> 7;
}
/*
* Check for a restart marker & resynchronize decoder.
*/
LOCAL(void)
process_restart (j_decompress_ptr cinfo)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci;
jpeg_component_info * compptr;
/* Advance past the RSTn marker */
if (! (*cinfo->marker->read_restart_marker) (cinfo))
ERREXIT(cinfo, JERR_CANT_SUSPEND);
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* Re-initialize statistics areas */
if (cinfo->progressive_mode == 0 || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
MEMZERO(entropy->dc_stats[compptr->dc_tbl_no], DC_STAT_BINS);
/* Reset DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
if (cinfo->progressive_mode == 0 || cinfo->Ss) {
MEMZERO(entropy->ac_stats[compptr->ac_tbl_no], AC_STAT_BINS);
}
}
/* Reset arithmetic decoding variables */
entropy->c = 0;
entropy->a = 0;
entropy->ct = -16; /* force reading 2 initial bytes to fill C */
/* Reset restart counter */
entropy->restarts_to_go = cinfo->restart_interval;
}
/*
* Arithmetic MCU decoding.
* Each of these routines decodes and returns one MCU's worth of
* arithmetic-compressed coefficients.
* The coefficients are reordered from zigzag order into natural array order,
* but are not dequantized.
*
* The i'th block of the MCU is stored into the block pointed to by
* MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
*/
/*
* MCU decoding for DC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl, sign;
int v, m;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* Outer loop handles each block in the MCU */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
tbl = cinfo->cur_comp_info[ci]->dc_tbl_no;
/* Sections F.2.4.1 & F.1.4.4.1: Decoding of DC coefficients */
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.19: Decode_DC_DIFF */
if (arith_decode(cinfo, st) == 0)
entropy->dc_context[ci] = 0;
else {
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
sign = arith_decode(cinfo, st + 1);
st += 2; st += sign;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) (((INT32) 1 << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) (((INT32) 1 << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] = 12 + (sign * 4); /* large diff category */
else
entropy->dc_context[ci] = 4 + (sign * 4); /* small diff category */
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
entropy->last_dc_val[ci] += v;
}
/* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */
(*block)[0] = (JCOEF) (entropy->last_dc_val[ci] << cinfo->Al);
}
return TRUE;
}
/*
* MCU decoding for AC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int tbl, sign, k;
int v, m;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* There is always only one block per MCU */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
/* Sections F.2.4.2 & F.1.4.4.2: Decoding of AC coefficients */
/* Figure F.20: Decode_AC_coefficients */
for (k = cinfo->Ss; k <= cinfo->Se; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (arith_decode(cinfo, st)) break; /* EOB flag */
while (arith_decode(cinfo, st + 1) == 0) {
st += 3; k++;
if (k > cinfo->Se) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* spectral overflow */
return TRUE;
}
}
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
entropy->ac_stats[tbl][245] = 0;
sign = arith_decode(cinfo, entropy->ac_stats[tbl] + 245);
st += 2;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
if (arith_decode(cinfo, st)) {
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
}
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
/* Scale and output coefficient in natural (dezigzagged) order */
(*block)[jpeg_natural_order[k]] = (JCOEF) (v << cinfo->Al);
}
return TRUE;
}
/*
* MCU decoding for DC successive approximation refinement scan.
*/
METHODDEF(boolean)
decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
unsigned char st[4];
int p1, blkn;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
/* Outer loop handles each block in the MCU */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
st[0] = 0; /* use fixed probability estimation */
/* Encoded data is simply the next bit of the two's-complement DC value */
if (arith_decode(cinfo, st))
MCU_data[blkn][0][0] |= p1;
}
return TRUE;
}
/*
* MCU decoding for AC successive approximation refinement scan.
*/
METHODDEF(boolean)
decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
JCOEFPTR thiscoef;
unsigned char *st;
int tbl, k, kex;
int p1, m1;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* There is always only one block per MCU */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */
/* Establish EOBx (previous stage end-of-block) index */
for (kex = cinfo->Se + 1; kex > 1; kex--)
if ((*block)[jpeg_natural_order[kex - 1]]) break;
for (k = cinfo->Ss; k <= cinfo->Se; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (k >= kex)
if (arith_decode(cinfo, st)) break; /* EOB flag */
for (;;) {
thiscoef = *block + jpeg_natural_order[k];
if (*thiscoef) { /* previously nonzero coef */
if (arith_decode(cinfo, st + 2))
if (*thiscoef < 0)
*thiscoef += m1;
else
*thiscoef += p1;
break;
}
if (arith_decode(cinfo, st + 1)) { /* newly nonzero coef */
entropy->ac_stats[tbl][245] = 0;
if (arith_decode(cinfo, entropy->ac_stats[tbl] + 245))
*thiscoef = m1;
else
*thiscoef = p1;
break;
}
st += 3; k++;
if (k > cinfo->Se) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* spectral overflow */
return TRUE;
}
}
}
return TRUE;
}
/*
* Decode one MCU's worth of arithmetic-compressed coefficients.
*/
METHODDEF(boolean)
decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
jpeg_component_info * compptr;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl, sign, k;
int v, m;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* Outer loop handles each block in the MCU */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
/* Sections F.2.4.1 & F.1.4.4.1: Decoding of DC coefficients */
tbl = compptr->dc_tbl_no;
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.19: Decode_DC_DIFF */
if (arith_decode(cinfo, st) == 0)
entropy->dc_context[ci] = 0;
else {
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
sign = arith_decode(cinfo, st + 1);
st += 2; st += sign;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) (((INT32) 1 << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) (((INT32) 1 << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] = 12 + (sign * 4); /* large diff category */
else
entropy->dc_context[ci] = 4 + (sign * 4); /* small diff category */
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
entropy->last_dc_val[ci] += v;
}
(*block)[0] = (JCOEF) entropy->last_dc_val[ci];
/* Sections F.2.4.2 & F.1.4.4.2: Decoding of AC coefficients */
tbl = compptr->ac_tbl_no;
/* Figure F.20: Decode_AC_coefficients */
for (k = 1; k < DCTSIZE2; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (arith_decode(cinfo, st)) break; /* EOB flag */
while (arith_decode(cinfo, st + 1) == 0) {
st += 3; k++;
if (k >= DCTSIZE2) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* spectral overflow */
return TRUE;
}
}
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
entropy->ac_stats[tbl][245] = 0;
sign = arith_decode(cinfo, entropy->ac_stats[tbl] + 245);
st += 2;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
if (arith_decode(cinfo, st)) {
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
}
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
(*block)[jpeg_natural_order[k]] = (JCOEF) v;
}
}
return TRUE;
}
/*
* Initialize for an arithmetic-compressed scan.
*/
METHODDEF(void)
start_pass (j_decompress_ptr cinfo)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci, tbl;
jpeg_component_info * compptr;
if (cinfo->progressive_mode) {
/* Validate progressive scan parameters */
if (cinfo->Ss == 0) {
if (cinfo->Se != 0)
goto bad;
} else {
/* need not check Ss/Se < 0 since they came from unsigned bytes */
if (cinfo->Se < cinfo->Ss || cinfo->Se >= DCTSIZE2)
goto bad;
/* AC scans may have only one component */
if (cinfo->comps_in_scan != 1)
goto bad;
}
if (cinfo->Ah != 0) {
/* Successive approximation refinement scan: must have Al = Ah-1. */
if (cinfo->Ah-1 != cinfo->Al)
goto bad;
}
if (cinfo->Al > 13) { /* need not check for < 0 */
bad:
ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
}
/* Update progression status, and verify that scan order is legal.
* Note that inter-scan inconsistencies are treated as warnings
* not fatal errors ... not clear if this is right way to behave.
*/
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
int coefi, cindex = cinfo->cur_comp_info[ci]->component_index;
int *coef_bit_ptr = & cinfo->coef_bits[cindex][0];
if (cinfo->Ss && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
if (cinfo->Ah != expected)
WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
coef_bit_ptr[coefi] = cinfo->Al;
}
}
/* Select MCU decoding routine */
if (cinfo->Ah == 0) {
if (cinfo->Ss == 0)
entropy->pub.decode_mcu = decode_mcu_DC_first;
else
entropy->pub.decode_mcu = decode_mcu_AC_first;
} else {
if (cinfo->Ss == 0)
entropy->pub.decode_mcu = decode_mcu_DC_refine;
else
entropy->pub.decode_mcu = decode_mcu_AC_refine;
}
} else {
/* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
* This ought to be an error condition, but we make it a warning because
* there are some baseline files out there with all zeroes in these bytes.
*/
if (cinfo->Ss != 0 || cinfo->Se != DCTSIZE2-1 ||
cinfo->Ah != 0 || cinfo->Al != 0)
WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
/* Select MCU decoding routine */
entropy->pub.decode_mcu = decode_mcu;
}
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* Allocate & initialize requested statistics areas */
if (cinfo->progressive_mode == 0 || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
tbl = compptr->dc_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->dc_stats[tbl] == NULL)
entropy->dc_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, DC_STAT_BINS);
MEMZERO(entropy->dc_stats[tbl], DC_STAT_BINS);
/* Initialize DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
if (cinfo->progressive_mode == 0 || cinfo->Ss) {
tbl = compptr->ac_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->ac_stats[tbl] == NULL)
entropy->ac_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, AC_STAT_BINS);
MEMZERO(entropy->ac_stats[tbl], AC_STAT_BINS);
}
}
/* Initialize arithmetic decoding variables */
entropy->c = 0;
entropy->a = 0;
entropy->ct = -16; /* force reading 2 initial bytes to fill C */
/* Initialize restart counter */
entropy->restarts_to_go = cinfo->restart_interval;
}
/*
* Module initialization routine for arithmetic entropy decoding.
*/
GLOBAL(void)
jinit_arith_decoder (j_decompress_ptr cinfo)
{
arith_entropy_ptr entropy;
int i;
entropy = (arith_entropy_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(arith_entropy_decoder));
cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
entropy->pub.start_pass = start_pass;
/* Mark tables unallocated */
for (i = 0; i < NUM_ARITH_TBLS; i++) {
entropy->dc_stats[i] = NULL;
entropy->ac_stats[i] = NULL;
}
if (cinfo->progressive_mode) {
/* Create progression status table */
int *coef_bit_ptr, ci;
cinfo->coef_bits = (int (*)[DCTSIZE2])
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
cinfo->num_components*DCTSIZE2*SIZEOF(int));
coef_bit_ptr = & cinfo->coef_bits[0][0];
for (ci = 0; ci < cinfo->num_components; ci++)
for (i = 0; i < DCTSIZE2; i++)
*coef_bit_ptr++ = -1;
}
}

2
jdmaster.c
View File

@ -373,7 +373,7 @@ master_selection (j_decompress_ptr cinfo)
jinit_inverse_dct(cinfo);
/* Entropy decoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
jinit_arith_decoder(cinfo);
} else {
if (cinfo->progressive_mode) {
#ifdef D_PROGRESSIVE_SUPPORTED

6
jdtrans.c
View File

@ -100,9 +100,9 @@ transdecode_master_selection (j_decompress_ptr cinfo)
cinfo->buffered_image = TRUE;
/* Entropy decoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
} else {
if (cinfo->arith_code)
jinit_arith_decoder(cinfo);
else {
if (cinfo->progressive_mode) {
#ifdef D_PROGRESSIVE_SUPPORTED
jinit_phuff_decoder(cinfo);

2
jerror.h
View File

@ -93,6 +93,7 @@ JMESSAGE(JERR_MISSING_DATA, "Scan script does not transmit all data")
JMESSAGE(JERR_MODE_CHANGE, "Invalid color quantization mode change")
JMESSAGE(JERR_NOTIMPL, "Not implemented yet")
JMESSAGE(JERR_NOT_COMPILED, "Requested feature was omitted at compile time")
JMESSAGE(JERR_NO_ARITH_TABLE, "Arithmetic table 0x%02x was not defined")
JMESSAGE(JERR_NO_BACKING_STORE, "Backing store not supported")
JMESSAGE(JERR_NO_HUFF_TABLE, "Huffman table 0x%02x was not defined")
JMESSAGE(JERR_NO_IMAGE, "JPEG datastream contains no image")
@ -170,6 +171,7 @@ JMESSAGE(JTRC_UNKNOWN_IDS,
JMESSAGE(JTRC_XMS_CLOSE, "Freed XMS handle %u")
JMESSAGE(JTRC_XMS_OPEN, "Obtained XMS handle %u")
JMESSAGE(JWRN_ADOBE_XFORM, "Unknown Adobe color transform code %d")
JMESSAGE(JWRN_ARITH_BAD_CODE, "Corrupt JPEG data: bad arithmetic code")
JMESSAGE(JWRN_BOGUS_PROGRESSION,
"Inconsistent progression sequence for component %d coefficient %d")
JMESSAGE(JWRN_EXTRANEOUS_DATA,

4
jmorecfg.h
View File

@ -266,7 +266,7 @@ typedef int boolean;
/* Encoder capability options: */
#undef C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
@ -282,7 +282,7 @@ typedef int boolean;
/* Decoder capability options: */
#undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */

2
jpegint.h
View File

@ -345,6 +345,7 @@ EXTERN(void) jinit_downsampler JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_forward_dct JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_huff_encoder JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_phuff_encoder JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_arith_encoder JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_marker_writer JPP((j_compress_ptr cinfo));
/* Decompression module initialization routines */
EXTERN(void) jinit_master_decompress JPP((j_decompress_ptr cinfo));
@ -358,6 +359,7 @@ EXTERN(void) jinit_input_controller JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_marker_reader JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_huff_decoder JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_phuff_decoder JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_arith_decoder JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_inverse_dct JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_upsampler JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_color_deconverter JPP((j_decompress_ptr cinfo));

11
makefile.cfg
View File

@ -80,7 +80,7 @@ LIBSOURCES= jcapimin.c jcapistd.c jccoefct.c jccolor.c jcdctmgr.c jchuff.c \
jdinput.c jdmainct.c jdmarker.c jdmaster.c jdmerge.c jdphuff.c \
jdpostct.c jdsample.c jdtrans.c jerror.c jfdctflt.c jfdctfst.c \
jfdctint.c jidctflt.c jidctfst.c jidctint.c jidctred.c jquant1.c \
jquant2.c jutils.c jmemmgr.c
jquant2.c jutils.c jmemmgr.c jaricom.c jcarith.c jdarith.c
# memmgr back ends: compile only one of these into a working library
SYSDEPSOURCES= jmemansi.c jmemname.c jmemnobs.c jmemdos.c jmemmac.c
# source files: cjpeg/djpeg/jpegtran applications, also rdjpgcom/wrjpgcom
@ -110,19 +110,19 @@ TESTFILES= testorig.jpg testimg.ppm testimg.bmp testimg.jpg testprog.jpg \
DISTFILES= $(DOCS) $(MKFILES) $(CONFIGFILES) $(SOURCES) $(INCLUDES) \
$(CONFIGUREFILES) $(OTHERFILES) $(TESTFILES)
# library object files common to compression and decompression
COMOBJECTS= jcomapi.$(O) jutils.$(O) jerror.$(O) jmemmgr.$(O) $(SYSDEPMEM)
COMOBJECTS= jcomapi.$(O) jutils.$(O) jerror.$(O) jmemmgr.$(O) jaricom.$(O) $(SYSDEPMEM)
# compression library object files
CLIBOBJECTS= jcapimin.$(O) jcapistd.$(O) jctrans.$(O) jcparam.$(O) \
jdatadst.$(O) jcinit.$(O) jcmaster.$(O) jcmarker.$(O) jcmainct.$(O) \
jcprepct.$(O) jccoefct.$(O) jccolor.$(O) jcsample.$(O) jchuff.$(O) \
jcphuff.$(O) jcdctmgr.$(O) jfdctfst.$(O) jfdctflt.$(O) \
jfdctint.$(O)
jfdctint.$(O) jcarith.$(O)
# decompression library object files
DLIBOBJECTS= jdapimin.$(O) jdapistd.$(O) jdtrans.$(O) jdatasrc.$(O) \
jdmaster.$(O) jdinput.$(O) jdmarker.$(O) jdhuff.$(O) jdphuff.$(O) \
jdmainct.$(O) jdcoefct.$(O) jdpostct.$(O) jddctmgr.$(O) \
jidctfst.$(O) jidctflt.$(O) jidctint.$(O) jidctred.$(O) \
jdsample.$(O) jdcolor.$(O) jquant1.$(O) jquant2.$(O) jdmerge.$(O)
jdsample.$(O) jdcolor.$(O) jquant1.$(O) jquant2.$(O) jdmerge.$(O) jdarith.$(O)
# These objectfiles are included in libjpeg.a
LIBOBJECTS= $(CLIBOBJECTS) $(DLIBOBJECTS) $(COMOBJECTS)
# object files for sample applications (excluding library files)
@ -317,3 +317,6 @@ rdbmp.$(O): rdbmp.c cdjpeg.h jinclude.h jconfig.h jpeglib.h jmorecfg.h jerror.h
wrbmp.$(O): wrbmp.c cdjpeg.h jinclude.h jconfig.h jpeglib.h jmorecfg.h jerror.h cderror.h
rdrle.$(O): rdrle.c cdjpeg.h jinclude.h jconfig.h jpeglib.h jmorecfg.h jerror.h cderror.h
wrrle.$(O): wrrle.c cdjpeg.h jinclude.h jconfig.h jpeglib.h jmorecfg.h jerror.h cderror.h
jcarith.$(O): jcarith.c jinclude.h jconfig.h jpeglib.h jmorecfg.h jpegint.h jerror.h
jdarith.$(O): jdarith.c jinclude.h jconfig.h jpeglib.h jmorecfg.h jpegint.h jerror.h
jaricom.$(O): jaricom.c jinclude.h jconfig.h jpeglib.h jmorecfg.h jpegint.h jerror.h